Probing the distribution of gliadin proteins in dough and baked bread using conjugated quantum dots as a labeling tool

Abstract In this study, Quantum dots (QDs) were conjugated to gliadin antibodies and used as fluorescent probes to track gliadin proteins in dough and baked bread samples. QDs conjugated to gliadin antibody were specifically bound to gliadin to determine its molecular distribution in two different unleavened flat bread samples prepared at various baking times and compared with the uncooked dough. The specificity of gliadin antibody to gliadin was shown successfully with a Western Blot experiment excluding binding to all other hard wheat flour proteins. Confocal laser scanning microscopy (CLSM) was used to monitor QDs-gliadin antibody conjugates and obtain images of the distribution of gliadin in the dough and flat bread matrix as a function of baking conditions. The mean intensity value of gliadin for each sample was calculated and plotted. CLSM images showed significant changes in the distribution of fluorescence intensity generated by the gliadin-QD conjugate with baking time. The analysis of variance (ANOVA) was used to validate the statistical significance of the variation in mean intensity values of gliadin in different samples and sections. Based on all the aggregate intensity data gathered, we concluded that gliadin is distributed non-uniformly in different layers (top, center, and bottom) that were analyzed as well as between dough and flat bread samples baked at different times. Baking time and the location of layers in flat bread play a significant role in the distribution of gliadin proteins.